After being contacted by the ABC, the Australian Communications and Media Authority (ACMA) said it was trying to determine if these sites were in breach of the Interactive Gambling Act (IGA).

The IGA prohibits website operators from offering casino-style games and live sports betting to Australian customers.

Gambling operators without an Australian licence are also prohibited from taking bets from Australian customers.

"When deciding if a site should be investigated, the ACMA considers a number of factors, including whether the service being provided may be a prohibited or unlicensed service … and whether it may have an Australian-customer link," an ACMA spokesman said.

Dr Charles Livingstone, a gambling law expert from Monash University, said the sites do appear to have breached the act.

"The avowed purpose of the IGA is to protect Australians from less well-regulated gambling sites, and to prohibit non-wagering gambling being available online," he said.

"Using a web address of an Australian territory to offer online gambling services is an offence, unless the provider is registered in an Australian jurisdiction."

However, ACMA has only limited capacity to act against illegal betting sites.

As it does not regulate the internet domain registries that oversee the allocation of web addresses, ACMA must "seek to work co-operatively" with them, a spokesman said.

"[They] may be able to assist us in our investigation or enforcement activities, and can play a role in raising awareness of Australian interactive gambling laws with gambling operators."

Verisign, the American company which manages the registry for .cc sites, says it works with authorities "when informed that domain names … we are operating are allegedly involved in illegal activities".

"When we are presented with an order from a court from a competent jurisdiction impacting domain names within our registries, we take the specified action within our technical capabilities."

A number of the sites being looked at by ACMA have been approached for comment.